The present invention is related to a power limitation transformer circuit structure of power supply, which is able to maintain a nominal output power of a power supply, while meeting the relevant international safety regulation so as to ensure safety in use.
Due to advanced technologies, the manufacturing cost for electric products such as notebook-type computers, PDA and mobile phones is rapidly lowered. However, a short circuit or override of the power supply of such electric product may take place due to mis-operation or old circuit. Such circumstance may lead to a fire. Accordingly, it is recommended by specialists that a user unplug the plug of the electric product when not used. However, the electric products such as computer systems and internet systems are often kept in an always on state so that the short circuit still may happen. Moreover, it is known that it is necessary to radiate the heat generated by the electric product so as to protect the parts thereof from being damaged. Accordingly, the housing of the electric product is generally formed with heat-radiating slots and heat-radiating plates and/or a heat-radiating fan is added to the electric product for quickly dissipating the heat. The larger the size of the heat-radiating slot is, the better the heat-radiating effect is. However, in the case that the heat-radiating slot has too large size, alien articles may get into the electric product to lead to short circuit or malfunction thereof.
In order to avoid the above problem, IEC regulates a safety specification standard in which it is regulated that the width of the heat-radiating slot should not exceed 1 mm. In the case that the output power of the power supply is not over 100 W, the limitation of the width of the heat-radiating slot is negligible.
Most of the housings of the electric products such as portable computers are made of plastic materials. Therefore, in the case that the width of the heat-radiating slot is limited to be smaller than 1 mm, by means of the existent injection molding technique, it is very hard to manufacture the housing with so small heat-radiating slots.
With respect to the second situation, the output power of the power supply is limited to be less than 100 W. This can be hardly achieved in relevant computer products which will consume more than 100 W power due to increased accessory equipment.
Therefore, it is necessary to provide a measure which can ensure safety in use of electric products, while maintaining a nominal output power.
It is therefore a primary object of the present invention to provide a power limitation transformer circuit structure of power supply, which is able to maintain a nominal output power of a power supply, while meeting the relevant international safety regulation so as to ensure safety in use.
It is a further object of the present invention to provide the above power limitation transformer circuit structure of power supply, which meets the relevant safety regulation or standard without lowering the ratio of good products or increasing the manufacturing cost.
It is still a further object of the present invention to provide the above power limitation transformer circuit structure of power supply, in which the output power of the power supply is limited to be within a safety value. Therefore, in case of short circuit or override, no spark is generated so as to ensure safety.
It is still a further object of the present invention to provide the above power limitation transformer circuit structure of power by which the housing of the electric product can be made of plastic material with lower fireproof degree. Therefore, the processing is facilitated and the cost for the material and the production is lowered.
It is still a further object of the present invention to provide the above power limitation transformer circuit structure of power in which the thickness of the housing of the electric product can be reduced (for the fireproof degree is lowered) so that the accommodating space of the housing is enlarged. Therefore, the standard parts can be used instead of those parts with special size. Accordingly, the cost is further reduced.
The present invention can be best understood through the following description and accompanying drawings wherein: